Thermochemistry: Quiz

Question 1

True or False

A synthesis reaction is an endothermic process.

Answer 1

False

Question 2

The study of heat flow and heat measurement that accompanies chemical equation is called:

Answer 2

Calorimetry

Question 3

When applying the first law of thermodynamics to a system, when is heat a negative quantity?

-When heat is released by the system
-When no work is done either on the system or by the system
- When heat is absorbed by the system
-Heat can never be negative

Answer 3

When heat is released by the system

Question 4

An aqueous solution becomes hot when a solid is dissolved in it. What does the increase in temperature imply?

The solid absorbs heat.
The solid is insoluble.
The process is endothermic
The process is exothermic.

Answer 4

The process is exothermic.

Question 5

Which of the following physical processes is exothermic?
Boiling of water
Melting of ice
Evaporation of alcohol
Condensation of water vapor

Answer 5

Condensation of water vapor

Question 6

Which of the following can happen in a closed system?

Matter and energy to cross a system boundary
Neither matter nor energy to cross a system boundary
Only energy to cross a system boundary
Only matter to cross a system boundary

Answer 6

Only energy to cross a system boundary

Question 7

Which refers to the amount of energy required to raise one gram of a substance by 1oC?

Kinetic energy
Heat capacity
Specific hit
Specific heat

Answer 7

Specific heat

Question 8

How much energy is needed to change the temperature of 60.0 g of water by 15.0oC?

Note: The specific heat of water is 4.18J/g.oC.

250.8 J
3762 J
37.62 J
900 J

Answer 8

3762 J

60.0g * 15C * 4.18 J/g C = 3762 J

Question 9

A gas has constant pressure in a system. There is a loss of 45 J of heat in the surroundings around the system. 450 J of work is done on the system.

A. Find the system’s internal energy.

B. Determine whether it’s endothermic or exothermic.

-495 J, Exothermic
495 J, Endothermic
-405 J, Exothermic
405 J, Endothermic

Answer 9

495 J, Endothermic

(45) + (450) = 495

Question 10

What is the final temperature after 840 J is absorbed by 10.0 g water at 28oC?

Note:

The specific heat of water is 4.18J/g.oC.

20.1°C
48.1°C
1°C
8.1°C

Answer 10

48.1°C

(840/(10*4.18))+28C

Question 11

When looking up enthalpy values for a set of reaction species, the enthalpy depends on the _____.

color of the species
concentration of the species
amount of the species
physical state of the species

Answer 11

physical state of the species

Question 12

At what set of conditions do standard enthalpies occur?

100°C and 100 atm
0°C and 1.0 atm
25°C and 1.0 atm
100°C and 3.0 atm

Answer 12

25°C and 1.0 atm

Question 13

The standard enthalpy for an element in its reference form is defined as

-1 kJ/mol
0 kJ/mol
2 kJ/mol
1 kJ/mol

Answer 13

0 kJ/mol

Question 14

Which refers to the change in heat of a given reaction?

Entropy
Enthalpy
Free energy
Specific heat

Answer 14

Enthalpy

Question 15

What do you call the difference in the heat contents of the products and the reactants?

Kinetic energy
Heat of calorimetry
Temperature
Heat of a reaction

Answer 15

Heat of a reaction

Question 16

Considering the following hypothetical reactions, calculate the enthalpy change for the reaction A → C:

A → B; ∆H = 30 kJ

B → C; ∆H = 60 kJ

-90 kJ
30 kJ
-30 kJ
90 kJ

Answer 16

90 kJ

30+60 = 90

Question 17

Given the following enthalpies of the reaction, calculate the enthalpy change for the reaction: P4O6(s)+ 2 O2(g) → P4O10(s)

P4(s)+3O2(g) → P4O6(s) ∆H = –1640.1 kJ

P4(s)+ 5O2(g) → P4O10(s) ∆H = –2940.1 kJ

-4580.2 kJ
-1300 kJ
1,300 kJ
4580.2 kJ

Answer 17

-1300 kJ

+1640.1+(-2940.1)=-1300